Tropical Storm PHILIPPE

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TROPICAL STORM PHILIPPE DISCUSSION NUMBER 56
NWS NATIONAL HURRICANE CENTER MIAMI FL AL172011
1100 PM AST FRI OCT 07 2011
PHILIPPE HAS CHANGED LITTLE IN STRUCTURE DURING THE LAST SEVERAL
HOURS. STRONG SOUTHWESTERLY SHEAR...ESTIMATED TO BE AROUND 40
KT...HAS CAUSED THE LOW-LEVEL CENTER TO BE EXPOSED TO THE SOUTHWEST
OF A PERSISTENT AREA OF DEEP CONVECTION. A BLEND OF THE LATEST
DVORAK CI- AND T-NUMBERS STILL SUPPORTS AN INITIAL WIND SPEED OF 60
KT. CONTINUED HOSTILE UPPER-LEVEL WINDS...DRIER AIR ENTRAINING INTO
THE CYCLONE...AND DECREASING SEA SURFACE TEMPERATURES SHOULD CAUSE
THE TROPICAL STORM TO WEAKEN ON SATURDAY. PHILIPPE IS FORECAST TO
BECOME AN EXTRATROPICAL CYCLONE IN 24-36 HOURS WHEN IT MERGES WITH
A COLD FRONT. GLOBAL MODELS SHOW THE EXTRATROPICAL CYCLONE BECOMING
ABSORBED INTO A MUCH LARGER LOW PRESSURE SYSTEM OVER THE
NORTHEASTERN ATLANTIC IN FOUR TO FIVE DAYS.
THE TROPICAL STORM IS ACCELERATING TO THE EAST-NORTHEAST...AND THE
LATEST INITIAL MOTION ESTIMATE IS 075/14. A TURN TO THE NORTHEAST
WITH AN ADDITIONAL INCREASE IN FORWARD SPEED IS FORECAST AS A
DEEP-LAYER TROUGH SHARPENS AS IT APPROACHES PHILIPPE. AFTER
EXTRATROPICAL TRANSITION...THE CYCLONE IS EXPECTED TO TRACK
NORTH-NORTHEASTWARD UNTIL IT DISSIPATES.
THE POST-TROPICAL PORTION OF THIS FORECAST IS VERY CLOSE TO THE
GUIDANCE PROVIDED BY THE NOAA OCEAN PREDICTION CENTER. THE 34-KT AND
50-KT WIND RADII HAVE BEEN MODIFIED BASED ON A 0022 UTC ASCAT
OVERPASS.
FORECAST POSITIONS AND MAX WINDS
INIT 08/0300Z 30.7N 52.6W 60 KT 70 MPH
12H 08/1200Z 32.7N 49.5W 55 KT 65 MPH
24H 09/0000Z 36.6N 45.9W 50 KT 60 MPH
36H 09/1200Z 40.1N 43.2W 50 KT 60 MPH...POST-TROP/EXTRATROP
48H 10/0000Z 43.0N 40.5W 45 KT 50 MPH...POST-TROP/EXTRATROP
72H 11/0000Z 50.5N 34.0W 40 KT 45 MPH...POST-TROP/EXTRATROP
96H 12/0000Z 58.0N 29.0W 35 KT 40 MPH...POST-TROP/EXTRATROP
120H 13/0000Z...ABSORBED
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FORECASTER CANGIALOSI
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